Phosphorrückgewinnung aus Klärschlammaschen – Ergebnisse aus dem EU-Projekt SUSAN

Abstract

Phosphorus is an element essential to all living organisms and cannot be replaced in terms of its functions as a component of such molecules as DNA and RNA, and as key element in energy metabolism (ADP/ATP). Owing to their high phosphorus concentration (15-20% P2O5), sewage-sludge ash is a suitable secondary raw material for the production of P-fertilisers. However, considering the poor availability of phosphorus to plants and the presence of environmentally relevant heavy metals, direct agricultural use of such ash is not advisable. The EU Project SUSAN focuses on the development and optimisation of a thermochemical treatment method for sewage-sludge ash aiming to raise the fertilising effect of the ash to the level of conventional mineral fertilisers, such as Thomaskali and Single Super Phosphate SSP, and also to lower the heavy-metal concentrations to a level below the limits stipulated in the various fertiliser regulations of European countries. The extremely favourable results so far achieved by the SUSAN Project, as well as the economic considerations to which they have given rise, encourage large-scale technical implementation of the project. © 2008 Springer-Verlag.